Austin smiled at people in the public gallery as he went into the dock and shouted at police officers as he was taken to the cells.

Judge Jeremy Carey told Austin: “I have to sentence you for the gravest offence in the criminal calendar, namely murder.

"You were convicted by the jury on what I judge to be clear evidence."

The court earlier heard the 25-year-old drove after the victim and his friend Aaron Eldridge after they tried to con him over payment for crack cocaine and heroin by including paper among cash.

They had arranged to meet at flats in Grange Road, Gillingham, on January 23 and Austin – known as Guez or G – arrived in his Ford Mondeo estate with another man.

A police cordon around the car in Castlemaine Avenue. Picture: Andy Payton

The moment Austin drives directly at his victim - just before the fatal strike

Prosecutor Dominic Connolly said when the friends tried to con Austin out of the drugs he accused them of trying to rip him off.

There was a row and Mr O’Donohue and Mr Eldridge walked off along Castlemaine Avenue.

“Austin drove after them, went past them and turned round and drove his car at them,” said Mr Connolly.

“They jumped out of the way and started to run. Austin turned his car round and drove after them at speed.

“They ran up a grass verge and Austin drove his car up the verge. Mr Eldridge jumped out of the way. Mr O’Donohue did not.”

Police at the scene in Castlemaine Avenue, Gillingham, in January

John O'Donohue, 33, from Gillingham, died after being struck by Jake Austin's car

Austin drove his car straight at Mr O’Donohue and caused him fatal injuries when his head hit the windscreen.

The car carried on at speed, smashing through railings and over a retaining wall before stopping.

The court heard how Mr O'Donohue's common-law wife Zoe French had begged him not to take drugs from Austin.

He had insisted the deal would buy them a new stair carpet.

He was to be there as back-up to Mr Eldridge, and took a knife with him.

The judge today spoke of the “bizarre scene” of drugs being thrown up in exchange for Mr Eldridge giving back the car key fob he had snatched.

Police at the scene of a hit and run in in Castlemaine Avenue, Gillingham, in January.

“I have no doubt that all those involved were to a greater or lesser extent in a state of excitement and there were the beginnings of anger on your part that you had, as you put it, been ripped off.

“The matter would have, and should have, ended at the point where Aaron Eldridge and John O’Donohue got some of the crack cocaine and heroin they wanted for nothing and where you had got your fob back.

“You lied in the witness box, telling the jury that your intention at one point was to get away.

"Your intention from the point where you had been made to look a fool as a drug dealer not getting money for drugs was to get your revenge.

“It was an act of revenge from then on. You tried to explain to the jury that all you wanted to do was get your possessions back. That was roundly rejected by them, and rightly so."

Judge Jeremy Carey

CCTV footage showed Austin driving furiously down Castlemaine Avenue after the two men “who by now must have been terrified”.

Mr O’Donohue was on his right and Mr Eldridge on his left, and it was pure chance he went for Mr O’Donohue.

“You compounded your grave crime by acting in the most callous of fashions. Opening the door and seeing a man dying to your right, you simply kicked his leg to see if he was still alive" - Judge Jeremy Carey

“You mowed him down,” the judge continued. “You saw him without doubt in your headlights and you deliberately drove at him at a speed of some 35mph.

“His head broke the windscreen of the car and he was effectively fatally injured. You crashed through the fence taking his body with your car.

“Then you compounded your grave crime by acting in the most callous of fashions. Opening the door and seeing a man dying to your right, you simply kicked his leg to see if he was still alive.

“You searched for your belongings and made off into the night. Moreover, you then wove a web of lies to cover your tracks involving your innocent mother to report to the police a stolen vehicle.

Judge Carey said the “seemingly pathetic figure” of Austin later sobbing to his girlfriend Natalie Cox on the steps of flats in London was no more than self-pity, knowing the net was closing.

“I have no doubt you are an extremely dangerous man who loses his temper easily, as demonstrated by your actions that night,” he said.

“It was, as your counsel said, a loss of temper case but to simply state it in that way does not fully reflect the gravity of your offending.

Floral tributes left at the scene in memory of John O'Donohue

“You were grossly out of control in the generally accepted sense. My judgement is that renders you likely to be a danger for a very considerable period of time beyond today.”

Drug-dealing was something Austin effectively did for a living but the judge said he could not be sure he intended to kill the victim.

“Your utter rage was one where it seems to me you didn’t care as to your actions whether death or serious injury ensued. Indeed, the matter was given no thought by you at all.

“You cannot claim to be other than a seasoned criminal.”

The car on the railings

Judge Carey stressed to Austin: “The parole board will never release you unless and until it is satisfied you no longer pose a danger to the public.

"It should not be assumed that the tariff expressed by this court ensures you will be automatically released."

The victim died in a London hospital from multiple fractures to his head shortly afterwards.